1. Field of the Invention
The present invention relates to pattern forming methods and apparatus, exposure methods and apparatus, and device manufacturing methods and devices, and more particularly, to a pattern forming method and a pattern forming apparatus to form a pattern in a divided area on an object using a variable shaped mask, an exposure method and an exposure apparatus to expose an object with an energy beam via the pattern forming apparatus, and a device manufacturing method using the pattern forming method or the exposure method, and a device manufactured with the device manufacturing method.
2. Description of the Background Art
Conventionally, in a lithography process for manufacturing electron devices (microdevices) such as semiconductor devices or liquid crystal display devices, a projection exposure apparatus is used that transfers a pattern formed on a mask (such as a reticle, or a photomask) onto a substrate (such as a glass plate, or a wafer), on which a sensitive agent such as a resist is coated, via a projection optical system.
In recent years, various scanning exposure apparatus of a so-called maskless type have been proposed, which use a variable shaped mask (which is also called an active mask) instead of a costly mask (a mask which is a fixed pattern master), regardless of size of a device pattern. As a kind of this maskless type scanning exposure apparatus, a scanning exposure apparatus that uses a micromirror array which is a type of a reflective spatial light modulator, as a variable shaped mask, has been proposed (e.g., see Kokai (Japanese Unexamined Patent Application Publication) No. 2004-327660). According to the scanning exposure apparatus that uses the micromirror array as a variable shaped mask, by changing a pattern generated at a variable shaped mask in synchronization with scanning of a substrate stage in a scanning direction and by exposing a substrate held on the substrate stage, a desired pattern can be formed on the substrate without difficulty, and also cost reduction and downsizing of the apparatus are possible.
However, in the scanning exposure apparatus that uses the micromirror array as the variable shaped mask, since it is relatively difficult to increase the size of the micromirror array, an illumination area (pattern formation area) on the substrate is so small (e.g. the width in a non-scanning direction (a direction orthogonal to a scanning direction in a plane parallel to the surface of the substrate) is about 0.2 mm). Therefore, in the case of using a wafer with a diameter of 300 mm as the substrate, in order to expose one wafer (assuming that the entire surface of the wafer is exposed), the wafer needs to be scanned in the scanning direction at least about 1,500 times (750 round trips), which takes a long time.
Therefore, in the case of the scanning exposure apparatus of a maskless type, there is a possibility that temperature variation of the atmosphere in the vicinity of the substrate stage or the like occurs during exposure of one substrate, and due to the temperature variation, the measurement values of a measurement device (such as a laser interferometer) used for position measurement of the substrate stage vary, which causes measurement error. In addition, there is also a risk that the exposure accuracy is lowered due to the measurement error.
Further, because the illumination area (pattern formation area) on the substrate is so small, it is difficult to expose a shot area with a size of 25 mm×33 mm on the wafer at one time. Meanwhile, in an exposure apparatus such as a liquid crystal exposure apparatus, a method is employed in which a plurality of projection optical systems are placed in a zigzag shape and a projection area (illumination area) of a mask pattern by each of the projection optical systems is set to have a trapezoidal shape using a field stop. When this method is employed for screen stitching in an exposure apparatus using a micromirror array, however, it is inefficient because some of micromirrors of the micromirror array are not used all through the exposure. Therefore, development of the pattern forming technologies, which are suitable for performing screen stitching with the variable shaped mask, has been expected.